The crank-slider mechanism is an ancient and proven method for converting rotary to linear motion, in which the crank can be turned repeatedly and continuously as there are no dead centers. The resulting linear motion is however reciprocal, as in the reciprocating piston pump.
When the same mechanism is used in reverse to convert linear to rotary motion, it is however interrupted by dead centers, which limit the rotation to 180 degrees. FIG. 1 shows the names of the principal parts in a slider-crank mechanism, as shown in the Encyclopedia Britannica. FIG. 2 and FIG. 3 show a slider-crank mechanism with the usual straight connecting rod, showing the dead center positions at 3 o'clock and 9 o'clock.
Historically the problem of dead centers has been adequately solved in industrial applications, including for example the use of accessory or secondary rods in the steam locomotive, or the use of the momentum generated by the fly-wheel effect, or the use of multiple slider-crank mechanisms with each rod working on a different phase of the rotation. However the use of these methods inevitably makes the overall apparatus larger and more complicated, and therefore not suitable for miniature use.
For miniature use a slider-crank mechanism needs to have a simpler method of avoiding dead centers, which is currently lacking. Any slider-crank mechanism for converting linear to rotary motion, unhampered by dead centers would find uses in hand instruments, gadgets, or robots, or in any situation where size and space are limited. The only limiting factor would then be the diameter of the rotating element, but not the length of the slide nor the push rod.